Acquisitions (2013 Acquisitions) (Narrative) (Details)	6 Months Ended
	Jun. 30, 2014
Big Country [Member]
Business Acquisition [Line Items]
Business combinations, effective date	May 01, 2013
Business combinations, percentage of voting interests acquired	100.00%
Business combinations, name of acquired entity	Big Country Energy Services, Inc. and its affiliated operating companies (collectively, "Big Country").
Business combinations, description of acquired entity	Big Country is a North American oil and gas pipeline and facility construction services company, headquartered in Calgary, Alberta, Canada.
April 2013 Acquisitions [Member]
Business Acquisition [Line Items]
Business combinations, description of acquired entity	former subcontractor to its wireless business, which provides self-perform communications tower construction, installation, maintenance and other services in support of telecommunications infrastructure construction
August 2013 Acquisitions [Member]
Business Acquisition [Line Items]
Business combinations, description of acquired entity	electrical transmission services company, which focuses primarily on substation construction activities